This study is a prospective longitudinal data collection for late outcomes (due to HIV disease progression, treatment effects and/or an interaction of the two) and late treatment effects. The study is open to children who have participated in ACTG treatment trials and infants whose mother participated in ACTG perinatal treatment trials. Data collected included history, physical exam, neurocognitive testing, clinical and laboratory evaluations, morbidity, mortality and quality of life assessments at specific intervals. This is a long-term protocol that allows us to collect clinical data indefinitely.